Conventionally, a ceramic capacitor is generally formed by applying a paste comprising a fine silver oxide (AgO) powder as an electric conductive ingredient, and a low melting point glass frit incorporated therein on a dielectric ceramic body by means of a screen printing method or other means, followed by baking. This silver-baked electrode is advantageous in excellent electrical properties, good high frequency characteristics, and high reliability, as well as easy and simple production of an electrode film.
However, in the conventional silver-baked electrode, silver is an expensive material and there has been restriction to reduce the production cost.
Moreover, in the case where an external electrode such as a conductor pattern of printed circuit or a lead wire is soldered to the silver-baked electrode, since there is a high tendency to bring about so-called "solder leach phenomenon" in that silver is diffused and migrated into solder, the adhesion strength of the electrode to the ceramic body is in some cases lowered or deterioration in capacitor characteristics such as poor electrostatic capacity takes place.
Furthermore, migration of silver tends to occur, resulting in poor reliability such as a decrease in dielectric strength. In particular, since it is impossible to completely prevent a dielectric ceramic body from micro-cracks due to thermal shock in the course of soldering, there is a tendency that silver is diffused and migrated into the microcracks, so that the migration of silver becomes accelerated, resulting in reduced reliability.
As a means for overcoming the disadvantages of the conventional silver-baked electrode described above, a copper-baked electrode is proposed in JP-B-1-51003 (the term "JP-B" used herein means a Japanese examined patent publication). This copper-baked electrode comprises a fine copper powder and a glass frit comprising at least one member selected from lead borosilicate, bismuth borosilicate, and zinc borosilicate as main ingredients, in which the amount of the glass frit is 2 to 40% by volume based on the amount of the fine copper powder. The copper-baked electrode is formed by dispersing the fine copper powder and the glass frit into an organic vehicle to form a paste, applying the paste on a dielectric ceramic body by a method such as a screen printing, and baking it in a neutral atmosphere (nitrogen).
However, it is necessary for the copper-baked electrode to bake the paste at a high temperature of not less than 800.degree. C., so as to make the electrode dense. If the densification is insufficient, solder permeates into the electrode and causes deterioration in electrostatic capacity and terminal strength. Furthermore, copper, which is a base metal, must be baked in a neutral atmosphere to prevent oxidation, but baking in a neutral atmosphere at a high temperature proceeds with reduction of the dielectric ceramic body, which causes a lowered capacity when processed into a capacitor.